Process for the production of patterned tone-on-tone effects on a thermoplastic material



iwd t t s Pa PROCESS FOR THE PRODUCTION OF PATTERNED TONE-ON-TONE EFFECTS ON A THERMOPLAS- TIC MATERIAL Fred Fortess and Fred Best, Charlotte, N.C., assignors to Celanese Corporation of American-New York, N.Y .,-a corporation of Delaware a No Drawing. Filed Feb. 20, 19575 .110; 641,265 6 Claims. 01. 8- 14) This invention relates to.the. production of patterned effects in fabrics of cellulose acetate of high acetyl con-v the following detailed description and claims. In this description and claims all proportions unless otherwise indicated.

'In accordance with one aspect of this invention, a fabric of yarns of cellulose acetate of high acetyl conare by weight tent is embossed in a pattern by pressing aheated pat- 2,954,269 Patented Sept. 27, 1960 2 of the fabric being out of contact, or not pressed firmly into contact, with said heated embossing surface and herefore being at a lower temperature. The extent of embossing may be varied as desired. An embossing roll in which the raised surafces are ,5 inch above the remainder of the roll surface has been found very suitable for use with fabrics having thicknesses of about 4 to inch. The embossing treatment should not be so severe as to cause fusion of adjacent fibers and loss of the fibrous character of the fabric or to damage 7 said fabric, as by severing the fibers thereof.

After the embossing operation the fabric is dyed with a disperse cellulose acetate dyestuif, preferably in a heated aqueous dyebath containing a dispersing agent and, if desired, a dyeing assistant. The dyestuifxand dyeing assistant used, and the dyeing procedures employed, may be any of those described in the copending application ofV. S. Salvin et al., Serial ,No.-472,758, filed December 2, 1954. During dyeing the embossed fabric loses atleast a portion of its embossed texture a; and becomes flatter. The dyed fabric shows a patterned tone-on-tone effect, the portions of the fabric which had been in contact with the raised portions of, the heated embossing surface having a lighter appearance than the other portions of the fabric.

After dyeing the fabric is heat-treated. The eifect of this heat-treatment is to raise the safe-ironing point of terned embossing surface against said fabric. The em-.

bossed fabric is then dyed and, preferably, heat-treated. During dyeing and heat-treating the embossed effect on the fabric substantially disappears; that is, the fabric returns to substantially its original smooth texture, with the previously embossed portions in substantially the same plane as the unembossed portions. However, the resulting smooth fabric has a definite two-tone, or toneon-tone, appearance showing, by differences in shade, the pattern originally applied by embossing.

The cellulose acetate of high acetyl content referred to above has an acetyl value of at least 59%, preferably at least 61%, calculated as combined acetic acid. For best results, the cellulose acetate, before it is subjected to the treatment of this invention, is in that crystalline condition corresponding to a safe ironing temperature of below about 200 C. It is desirable that the fabric be composed entirely of fibers of the cellulose acetate of high acetyl content. However, fabrics composed of blends of fibers of cellulose acetate of high acetyl content with non-thermoplastic fibers such as cot-- ton, linen, wool, and rayon may also be used, although the results are not as good as when an unblended cellulose acetate of high acetyl content is used alone. Best results have been obtained with woven fabrics but the process of this invention may be applied to knitted, knotted or non-woven fabrics as well.

As stated, the embossing surface should be heated. Excellent results have been obtained when the embossing surface is at a temperature of about 200 C. to 220 C. In one convenient method the fabric is passed continuously into contact with a heated patterned metal embossing roll, being pressed resiliently against the raised portions of the embossing roll by means of a suitable smooth, resilient-surfaced pressure roll.

The embossing is carried out in such a manner that only portions of the fabric which are in contact with the raised portions of the heated embossing surface are subjected to the elevated temperature of said embossing surface, to achieve spot heat treatment, the other parts the fabric, as well :as to improve its resistance to glazing, its resistance to shrinkage on pressing with moist steam, and its 'wash fastness. The heat-treatment also increases the crystallinity and crystalline order index of the cellulose acetate of high acetyl content.

In the heat-treatment step the conditions disclosed in the aforesaid copending application of Salvin et al. may be employed. This heat-treatment results in a further flattening of the fabric so that substantially none of its original embossed texture remains.

It is desirable to apply a finish to the fabric before heat-treatment. One very suitable finish is the mixture comprising an aqueous dispersion of :a silicone and colloidal silica, described in Fortess et al. application Serial No. 529,073, filed August 17, 1955.

The tone-on-tone effect produced in accordance With this invention is highly resistant to washing and cleaning and the patterned fabrics of this invention have substantially the same hand, feel and drape as fabrics which have not undergone any embossing treatment. The same tone-on-tone effect is not produced when the same process is carried out except that the embossing is done after the dyeing, but before the heat treatment.

While this invention finds its greatest utility for fabtics of cellulose acetate of high acetyl value, the same treatment may also be used for fabrics of polyesters of high melting point, such as polyethylene terephthalate, to produce similar effects.

The following examples are given to illustrate this invention further.

Example I A woven fabric composed of fibers of cellulose acetate of acetyl value 61.5%, calculated as combined acetic acid, and having a safe ironing temperature of below 200 C. is passed into contact with a copper embossing roll having its surface formed in a small repeated'fourleaf-clover pattern. The embossing roll is maintained at a temperature of 210 C. and the fabric is pressed against the embossing roll by means of a smooth metal roll having a uniform paper cover. The time of contact between embossing roll and fabric is 0.04 second. The embossed fabric, in which the slightly raised outlines of the pattern are evident, is then dyed a medium blue shade in an aqueous dyebath containing 8% based 3 on the weight of the fabric, of Eastman Blue GLF (1,8 dihydroxy-5-nitro-4 alpha hydroxyethyl phenyl amino 'anthraquinone) and 1% based on the Weight of the fabric, of lgepon T Gel-(sodium tauryl sulfate).

Example II Example I is repeated except that a dyeing assistant (5 grams per liter of Emkala plus 3 grams per liter of Emkatex) is substituted for the Igepon T." The effect is the same as in Example I except that the shade of the fabric is darker.

Example III Example I is repeated except that the fabric is scoured after the embossing treatment and before dyeing. Also, just before the heat-treatment the fabric is finished with a silicone-silica fiinish as described in Fortess et a1. application Serial No. 529,073. The fiat, heat-treated fabric retains its tone-on-tone patterned appearance even after boiling for one hour.

Example IV Example In is repeated, except that the similar dye, Interchemical Blue GSF, is used. The results are substantially the same.

It is to be understood that the foregoing detailed description is given merely by Way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention what we desire to secure by Letters Patent is:

1. Process for the production of patterned tone-on-tone effect fabrics which comprises embossing, with a heated 5 surface at a temperature of about 200 to 220 C., a fabric of cellulose acetate of aoetyl value at least 59%, calculated as combined acetic acid, and then dyeing said fabric with a disperse cellulose acetate dyestuff and substantially removing the embossed texture of the fabric, to produce an unembossed flat fabric having a tone-on-tone pattern.

2. Process as set forth in claim 1, and comprising the step of heat-treating said fabric after dyeing to raise the safe ironing temperature of said fabric to at least 220 C., from an initial value, before embossing, of not over 200 C.

3. Process as set forth in claim 1 in which said acetyl values isatleast 61%.

4. Process as set forth in claim 1 in which said dyeing is carried out in a heated aqueous dyebath containing said dyestulf.

5. A fabric produced in accordance'with claim 1.

6. A fabric produced in accordance with claim 3.

The Technical Bulletin, pub. by the Du Pont Cot, September 1955, pp. 115-120. 

1. PROCESS FOR THE PRODUCTION OF PATTERNED TONE-ON-TONE EFFECT FABRICS WHICH COMPRISES EMBOSSING, WITH A HEATED SURFACE AT A TEMPERATURE OF ABOUT 200* TO 220*C., A FABRIC OF CELLULOSE ACETATE OF ACETYL VALUE AT LEAST 50%, CALCULATED AS COMBINED ACETIC ACID, AND THEN DYEING SAID FABRIC WITH DISPERSED CELLULOSE ACETATE DYESTUFF AND SUBSTANTIALLY REMOVING THE EMBOSSED TEXTURE OF THE FABRIC, TO PRODUCE AN UNEMBOSSED FLAT FABRIC HAVING A TONE-ON-TONE PATTERN. 